On June 5, 1981, the Centers for Disease Control and Prevention published a brief, clinical report in its Morbidity and Mortality Weekly Report about five young men in Los Angeles who had developed a rare and deadly form of pneumonia.  The write-up, barely a page long, ran in between a report on dengue infections among US travelers and an assessment of measles cases. No one who read it could have known this was the opening chapter of the deadliest infectious disease epidemic since the 1918 flu — one that would kill an estimated 44 million people worldwide and reshape medicine, politics, and culture in ways we’re still reckoning with. It would eventually be called human immunodeficiency virus, or HIV. For the next 15 years, an HIV diagnosis was, functionally, a death sentence, as the immune system was hollowed out on a slow march to full-blown AIDS. The virus mutated so rapidly that every early attempt at treatment felt like trying to hit a moving target in the dark.…